Fig. 4

Electron micrograph of chimeric 412–425_sHBsAg particles. After centrifugation on OptiPrep gradient, the particles were negatively stained with uranyl acetate and analyzed by electron microscopy (top). Numerous particles approximately 22 nm in diameter were observed. The exposition of the 412–425 epitope was studied by immunogold labeling using AP33 mAbs and secondary goat anti-mouse Abs conjugated with 6 nm gold particles (bottom). Scale bar 100 nm